Interpretation of ratings

While often very informative, the interpretation of results of non-quantitative cultures of bulk and swab samples is subjective. As a general rule, for fungi which are copious sporulators (e.g. moulds), we interpret a rating of less than 2+ as suggestive of passive contamination (e.g. spores which may have settled out form the ambient air, and not likely produced in situ on the test material). For the same group of fungi, ratings of 2+ are equivocal while ratings greater than 2+ are strongly suggestive of active contamination of the material sampled. More judicious interpretation must be used for fungi with low spore viability or longevity, weakly to non-sporulating taxa.